Sedimentological and geochemical characterization of river suspended particulate matter (SPM) sampled by time-integrated mass flux sampler (TIMS) in the Sava River (Croatia)

Purpose

Suspended particulate matter (SPM) plays a crucial role in the transport of natural and anthropogenic substances. However, obtaining a representative sample and a substantial amount of SPM in rivers, where the flux and quantity of SPM are highly episodic, can be a challenging task. To collect a sufficient quantity of SPM for detailed sedimentological and geochemical analysis, a time-integrated mass flux sampler (TIMS) was used for the sampling in a medium size river (the Sava River, Croatia).

Materials and methods

Sampling was conducted in August and October 2014, and February and May 2015 under different discharge conditions. The SPM collected by TIMS was characterized with respect to its particle size distribution (PSD), mineral content, and geochemical composition.

Results and discussion

PSD analysis identified silt as a dominant size fraction in all samples except in May 2015 when sand prevailed; subsequent chemical dispersion of samples revealed flocculation as the main factor responsible for the resulting PSD. The mineralogical composition of the SPM was quite constant (quartz, calcite, dolomite, feldspar, illite/muscovite, kaolinite), but the contribution of particular mineral varied depending on the sampling period. In May 2015, unusually high calcite content was determined. Though the dominant source is still uncertain, a portion of calcite is likely detrital in origin. Geochemical analyses of collected material revealed significant anthropogenic input of ecotoxic elements (Ni, As, Cr, Pb, Bi, Cd, Zn, Sb) primarily associated with the fine fraction of the Sava River SPM.

Conclusions

A considerable amount of the SPM was collected by TIMS, both during high and low river discharge. Sedimentological analyses of the Sava River SPM suggested the input of material from various sources during different river regimes. Geochemical composition of the SPM followed its sedimentological characteristics—preferential adsorption of trace elements to fine-grained clay mineral particles was documented. Some processes inside TIMS were observed during this investigation—the suspended material captured inside the sampler underwent additional changes. The flocculation of the colloidal material instigated by algal bloom was observed.

     

Alkaline Comet Assay as a Potential Tool in the Assessment of DNA Integrity in Freshwater Zooplankton Affected by Pollutants from Water Treatment Facility

Water, Air, & Soil Pollution - In this pilot study, we evaluated the usefulness of the alkaline comet assay as a biomonitoring tool at the level of plankton communities affected by varying...     

Sedimentary records of the Zrmanja River estuary,eastern Adriatic coast—natural vs. anthropogenic impacts

Purpose

Investigations of geochemical characteristics of sediments of the Zrmanja River estuary were done in order to determine the natural and anthropogenic factors influencing sediment composition in this area. For that purpose, spatial and temporal distribution of major and trace elements in the sediments and surrounding soils was studied.

Materials and methods

Sediment and soil samples, including one marl sample, were collected at 28 locations. All samples were subjected to total digestion and subsequently analysed by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for total concentration of 20 elements (Ag, Al, As, Be, Ca, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Rb, Sb, Sn, Sr, Ti and Y). Obtained concentrations and their normalized counterparts were used for assessment of factors influencing sedimentation in the study area.

Results and discussion

The results of the analysis showed that the composition of sediments of the Zrmanja River estuary is primarily determined by the composition of bedrock, existing hydrodynamic conditions and the relative isolation of the studied basin. Nevertheless, anthropogenic influences were observed as well. The composition of the Zrmanja River sediments reflects the impact of the ex-alumina factory “Jadral” and transfer by wind of the material from its immediate surroundings to the water system of the Zrmanja River. In addition, sedimentation in the Zrmanja River was found to be influenced by the construction of reservoirs and the HE “Velebit”, hydroelectric power plant located in the Zrmanja watershed.

Conclusions

The geochemical composition of recent sediments of the Zrmanja River estuary is controlled primarily by natural factors, although the influence of anthropogenic activities is also evident.

     

Composition and stability of soil aggregates in Fluvisols under forest,meadows, and 100 years of conventional tillage

Conversion of meadow and forest ecosystems to agricultural land generally leads to changes in soil structure. This comparative study presents the composition and stability of structural aggregates in humus horizons (0–30 cm) of noncarbonate silty‐clay Fluvisols in the Kolubara River Valley, W Serbia. Aggregates collected from under a native forest were compared to aggregates from meadows and arable fields which underwent crop rotation for > 100 y. The results show that size distribution and stability of structural aggregates in the humus horizons of arable soil are significantly impaired due to long‐term anthropogenization. In the humus horizons, the content of the agronomically most valuable aggregates (0.25–10 mm) decreased by a factor of ≈ 2, from 68%–74% to 37%–39%, while the percentage of cloddy aggregates (>10 mm) increased by a factor of ≈ 2, from 23%–31% to 48%–62%, compared to forest aggregates. The long‐term‐arable soil had significantly (p < 0.05) lower aggregate stability, determined by wet sieving, than meadow and forest soils. The lowest aggregate stability was found in aggregates > 3 mm. Their content is ≈ 2.5–3 times lower in arable soil (13%–16%) than in forest soil (32%–42%) at a depth of 0–20 cm. The largest mean weight diameters of dry aggregates (dMWD) with a range between 12.6 and 14.7 mm were found in arable soil, vs. 9.5–9.9 mm in meadow and 6.5–8.3 mm in forest. The arable soil had significantly lower mean weight diameters of wet‐stable aggregates (wMWD) and a lower structure coefficient (Ks) than forest and meadow soils. The dispersion ratio (DR) of arable soil was significantly higher than that of forest and meadow soils. Forest and meadow showed a significantly higher soil organic‐matter content (SOM) by 74% and 39%, respectively, compared with arable soil, while meadow uses decreased the SOM content by 57% compared with forest at a depth of 0–10 cm. In conclusion, the results showed that long‐term conventional tillage of soils from natural forest and meadow in the lowland ecosystems of W Serbia degraded soil aggregate–size distribution and stability and reduced SOM content, probably resulting in lower productivity and reduced crop yields.     

Impact of entomopathogenic nematodes on adults of Phyllotreta spp. (Coleoptera: Chrysomelidae) under laboratory conditions

Abstract

In 2005, preparations of four species of the entomopathogenic nematodes Steinernema feltiae, S. carpocapsae, Heterorhabditis bacteriophora, and H. megidis, were tested under laboratory conditions for their ability to kill adult flea beetles, Phyllotreta spp. (Coleoptera: Chrysomelidae). The nematode preparations were tested at doses of 200, 1000, and 2000 IJs per adult and at temperatures 15°C, 20°C, and 25°C. The numbers of beetles killed were recorded two, four, six, and eight days after treatment. The nematodes were more effective at 20°C and 25°C than at 15°C. At 20°C, the nematodes had killed between 44% (H. megidis at the lowest dose tested) and 77% (S. feltiae at the lowest dose tested) of the beetles eight days after treatment. At the two highest doses tested, the S. feltiae, S. carpocapsae, and H. bacteriophora preparations each killed at least 74% of the beetles at 25°C. Steinernema feltiae was the most effective nematode (LC₅₀=483–1467 IJs/adult) and, as an alternative to chemical insecticides, appears to have the highest potential for controlling overwintered flea beetles (May) under field conditions. The nematodes S. feltiae, S. carpocapsae and H. bacteriophora would all be suitable for controlling adult flea beetles during warm summer months, when flea beetles occur in high numbers in Slovenia.     

Drought effects on C,N, and P nutrition and the antioxidative system of beech seedlings depend on geographic origin

In future, prolonged summer drought and heat will constitute a major risk for the cultivation of shallow‐rooting beech in Central Europe and will negatively affect the productivity of beech forests. In a pot experiment under controlled conditions, the influence of long‐term (28 d) water deprivation on nitrogen (N), carbon (C), phosphate (P_i), and ascorbate (ASC) concentrations was examined in leaves and fine roots of beech seedlings (Fagus sylvatica L.) from six provenances originating from Central Europe (Germany: Neidenstein and Illertissen, intermediate habitats), the Balkan peninsula (Croatia: Zagreb and Gospic, wet habitats), and Southeast Europe (Bulgaria: Kotel, Greece: Paikos; dry habitats). The goal of the study was to identify beech provenances well adapted to water limitation during summer drought events. Our results suggest that N might be involved in the alleviation of water scarcity, whereas P_i might become a limiting factor for forest growth during drought periods. Drought stress resulted in significant changes of ASC pools in leaves and fine roots and the ASC redox state. Under well‐watered and under drought conditions, ASC in leaves was the most important factor causing differences between the provenances examined. Finally, a link between P nutrition and the capacity of antioxidative stress defense by ascorbate could be highlighted. Based on observations from this study, beech seedlings from three origins (Paikos, Zagreb, and Neidenstein) might constitute beech provenances well adapted to water shortage in summer. This conclusion is drawn from the high potential of these provenances to alleviate oxidative stress during water shortage.     

Linearity of eprinomectin pharmacokinetics in lactating dairy sheep following pour-on administration: excretion in milk and exposure of suckling lambs

Pharmacokinetics of eprinomectin (EPR) were studied in blood plasma and milk in two groups of six Istrian Pramenka dairy sheep and their suckling lambs following pour-on administration of EPR to ewes at dose levels of 0.5 and 1 mg/kg. Maximum concentration in plasma was 2.22 and 5.25 μg/l, and AUC was 13.6 and 33.7 μg day/l for the 0.5 and 1.0 mg/kg dose, respectively. These results indicate that drug exposure with a dose of 0.5 mg/kg, which is commonly used in cattle, may be subtherapeutic. The concentration time course in milk paralleled plasma concentrations. In the dose range studied, linear pharmacokinetics of EPR were demonstrated. Milk-to-plasma AUC ratio was 0.79 ± 0.12 and 1.12 ± 0.43; the fraction of dose recovered in milk was 0.037 ± 0.011 and 0.058 ± 0.027% for the low and high dose, respectively. Maximum residual levels in milk were below the maximum acceptable level of 20 μg/kg; however, EPR was detected in all samples investigated. Despite low permeability in milk, AUC in plasma of suckling lambs was between 20 and 30% of the AUC in plasma of ewes.     

Multi-criteria Analysis of Air Pollution with SO2 and PM10 in Urban Area Around the Copper Smelter in Bor, Serbia

This work presents the results of 4 years long monitoring of concentrations of SO₂ gas and PM₁₀ in the urban area around the copper smelter in Bor. The contents of heavy metals Pb, Cd, Cu, Ni, and As in PM₁₀ were determined and obtained values were compared to the limit values provided in EU Directives. Manifold excess concentrations of all the components in the atmosphere of the urban area of the townsite Bor were registered. Through application of a multi-criteria analysis by using PROMETHEE/GAIA method, the zones were ranked according to the level of pollution.     

Kinetics of abamectin disposition in blood plasma and milk of lactating dairy sheep and suckling lambs

Abamectin (ABM) has been used worldwide as an anthelmintic drug in veterinary medicine and as an agricultural pesticide. Its pharmacokinetics and permeation into milk was evaluated in dairy sheep after subcutaneous administration. ABM elimination half-lives and mean residence times were 1.7 and 3.7 days for blood plasma and 1.9 and 3.8 days for milk, respectively. The ABM milk to plasma concentration ratio (0.89) primarily depends on milk fat content. Transfer of ABM residues to suckling lambs was evaluated by determination of ABM concentration time courses in lambs' plasma. Mean maximal concentration in lambs was 1.6 microg L(-1) at 3.3 days, and elimination half-life was 2.7 days. In ewes' plasma and milk, ABM was detected up to 23 days. Because of different pharmacokinetics, ABM exposure in lambs was almost 10% of the exposure in ewes, although the amount excreted in milk was only 1.0% of the dose.     

Pore water geochemistry and diagenesis of estuary sediments—an example of the Zrmanja River estuary (Adriatic coast,Croatia)

Journal of Soils and Sediments - The geochemistry of pore waters from sediments deposited in the semi-enclosed bay of the Zrmanja River estuary, encompassing two small interconnected basins, the...